Due Dates:

• SPI Peripheral Setup - 10/4/2025

• Basic SD Read/Write -

• Full Implementation (RTOS) -

• Documentation -

Description/Purpose

• The Leader System-On-Module (LSOM) used on several critical boards on the car has a SPI-based SD card reader connected to the STM32 microcontroller on the board. This driver provides a thread-safe, robust interface to interact with this SD card reader.

Requirements

• Basic functionality - initialization, reading, writing from SD card

• Formatting?

• Thread safety - multiple tasks should be able to read/write the SD card without causing data races or corruption

Application Note

• STM32 SD Card Example

Steps for Debug

• Test for SPI Peripheral Setup using logic analyzer:

  • SPI2 GPIO Configuration
    SPI2_SCK: PB10
    SPI2_MISO: PC2
    SPI2_MOSI: PC3

  • CS: PB12

• Open

  

• Test for command send

• Test for SD_Init()

  • Requirements:

    1. To enter SPI mode, the host must send ≥74 dummy clocks with CS = high

    2. Send CMD0, puts the SD card into idle state (Expected response = 0x01 = idle)

    3. Open

       

       Send CMD0

        

    4. Send CMD8 (CHECK VOLTAGE / VERSION); send argument 0x000001AA and expect the same pattern back.

       • Open

         

         Send CMD8

          

       • CMD8 checks:

         Voltage range support (card must support 2.7–3.6V)

         SD version (SDv2 (R1 response is 0x01) vs SDv1/MMC (R1 response is 0x05))

         Echo-back check (lower 12 bits must be 0x1AA)

       • When you send CMD8, the SD card returns R7 (r7[4])

         r7[0] = 0x00 (always)

         r7[1] = 0x00 or 0x01 something (voltage) -> supports 2.7-3.6V

         r7[2] = 0x01 (upper byte of 0x1AA) -> match echo-back patter

         r7[3] = 0xAA (lower byte of 0x1AA) -> match echo-back patter

    5. Loop sending ACMD41 until the card leaves idle
       Send CMD55 (prefix command), Send ACMD41 (init command) until card returns: 0x00, meaning: “Initialization complete. Ready.”

    6. Send CMD58 to read Operating Conditions Register (supported voltage)

  • Meaning for different errors:

• Command Response:

• Test for FATFS

•